To connect a tube to an installation or to connect two tubes to each other, it is known to use rigid endpieces of the spigot type having Christmas-tree shaped teeth, in which the rigid endpiece possesses a cylindrical tubular portion fitted on its outside surface with catching sharp edges that retain the tube and that seal the connection once the cylindrical portion has been forced into the tube. The main drawback of such a device lies in difficulties associated with assembly and disassembly. In order to guarantee good retention and good sealing, the teeth must be of sufficient height to bite properly into the inside surface of the tube, and as a result hand assembly becomes extremely difficult since it is necessary to develop large engagement forces, and disassembly becomes practically impossible because the teeth penetrate into the inside wall of the tube and their substantially radial surfaces oppose a force tending to pull them out.
In certain applications, it is nevertheless useful to be able periodically to make and break connections between a tube to a rigid endpiece easily and by hand. This can be made easy by significantly reducing the height of the teeth, however that is to the detriment of the quality of retention and of sealing achieved between the endpiece and the tube.
To remedy this drawback, is it known to band the tube, once installed on the endpiece, with at least one collar or ring that is placed on the outside of the tube and that is clamped thereon by appropriate means.
Such devices provide mechanical qualities that are satisfactory, however connection and disconnection operations require enough time to operate the clamping means. Further, when connection and disconnection are frequent, the indentations formed repetitively by the collar in the tube end up by damaging the outside surface thereof and can lead to a weakening in the retention provided by the banding collar on the tube.
Quick coupling devices are also known for coupling a tube to a rigid endpiece, which devices comprise a female part secured to the rigid endpiece and a male tubular part fitted to the end of the tube to be coupled. The female part has a stepped bore including a large diameter portion capable of receiving a shoulder of the male part beyond an axial latch. The male part generally has an elongate portion with a cylindrical outside surface fitted with retention projections (e.g., Christmas-tree shaped teeth) for providing non-dismountable connection between the tube and the male part.
With that kind of device, initial coupling takes place in two stages. The tube must first be fitted on the male part and this requires large engagement force since the clamping must be strong enough to ensure that the connection is leakproof. Thereafter, the male part must be inserted into the female part until the shoulder of the male part has gone past the axial latch of the female part, with the connection being sealed by means of O-rings disposed between the two parts. The tube is disconnected by acting on the axial latch so as to decouple the male part from the female part.
That kind of device thus makes it possible to perform frequent connections and disconnections without damaging the mechanical qualities of the coupling formed. However, the structure comprising two separate male and female parts is inconvenient in use and initial coupling requires special tooling and handling for the purpose of engaging the tube on the male part.
U.S. Pat. No. 5,314,216, issued to UMEZAWA for THIN RESIN TUBE CONNECTING COUPLING WITH FLANGE INSERT, discloses a coupling provided with a body having opposed front and rear ends. A large diameter chamber extends into the rear end and a communication hole extends into the front end. A small diameter chamber connects the communication hole and the large diameter chamber. A split annular grip with an inwardly directed annular pawl is disposed in the small diameter chamber and is dimensioned for surrounding the tube. All of the components inserted in the staged bore are extracted therefrom, with the tube. In other words, the banding ring is not extracted by itself, as it is in the present invention. The banding ring cannot move with respect to the latch, with or without a tube. In the present invention, however, the banding ring may or may not pass the latch, depending on the radial position thereof.